ADC Frequency and Sample rate in LPC55xx

pejo — Wed, 03 Dec 2025 10:52:20 GMT

Hi!

I'm configuring ADC Conversion in my LPC5504.

Currently the configuration is the following:

* Main Clock: 96MHz

* ADCK Configuration:

- CLOCK_SetClkDiv to Prescaler = 2 (48MHz)

* 10 conversion operations:

- 9 with 35 ADCK cycles total sample time

- 1 with 131 ADCK cycles total sample time

* Conversion start trigger:

- Callback function in PWM at 10KHz

This is already working.

In the document from the NXP Knowledge base "ADC multi-channel sampling and DMA transfer in LPC55xx" it is said that maximum frequency is 24MHz but as I said we selected ADCK to 48MHz.

Question #1 Should we set a smaller prescaler (4 instead) according to this limitation or we could even use prescaler=1 ?

In this same document and in the user manual it is said that maximum sample conversion is 1 Mega samples per second. In our case we are doing 10 conversions at 10kHz which are 100,000 conversions pers second

Question #2 should I understand that we are still under the limitation of 1MSPS ?

Re: ADC Frequency and Sample rate in LPC55xx

Alice_Yang — Mon, 08 Dec 2025 03:56:51 GMT

Hello @pejo

For details about the ADC clock frequency and sample rate, please refer to the Datasheet.

Thank you.

Alice

LPC Microcontrollers中的主题 ADC Frequency and Sample rate in LPC55xx

ADC Frequency and Sample rate in LPC55xx

Re: ADC Frequency and Sample rate in LPC55xx